Currently, there are numerous different types of wireless communications networks and each of these networks may operate by utilizing a different communications technology. For example, while most European wireless networks operate using Global System for Mobile Communications (GSM) technology, many wireless communications networks in the United States operate using a different Time Division Multiple Access (TDMA) technology. Even within any particular country, different wireless communications providers may use different types of networks. For example, in the United States some wireless providers use GSM while others operate using a different TDMA technology or even Code Division Multiple Access (CDMA) technology.
Wireless communications networks which operate using these different technologies are generally incompatible. However, it may be desirable for a mobile communications device, e.g., a mobile phone, to be able to communicate in these different technologies, for example when roaming in a visited network.
Generally, any one cellular communications provider, particularly in the United States, does not have a network infrastructure that can provide service throughout the entire United States for its customers. Therefore, these cellular communications providers execute agreements with one or more other carriers to provide wireless services to each others' subscribers when the subscribers are out of their home network's coverage area but are in an area covered by one of these other carriers. Thus, these roaming agreements are commonly used where one carrier can not offer service in all of the areas where it's customers may require service. However, as discussed above, because these networks may utilize different communications technologies, mobile stations are increasingly designed with a “dual-mode” capability to allow them to communicate in different technologies. Thus, the mobile station communicates with it's home network using one mode, or technology, and with a visited network in a second mode, or technology, when roaming in that network. For example, the home network may use one TDMA technology and the visited network may use GSM technology. In this circumstance, the dual-mode mobile station communicates with it's home network in the TDMA mode and with the visited network in the GSM mode when roaming in the visited network.
Therefore, a dual-mode mobile phone is able to communicate in two technologies. In a particular circumstance, the dual-mode phone may have one mode which uses a standards-based technology and a second mode which uses a proprietary technology. In this circumstance, the standards-based technology may be the technology used when roaming in a visited network and the proprietary technology may be the technology used in the phone's home network. Since there are advantages to using standards-based technology, it may be desirable for the mobile phone to use the standards-based technology even when the phone is communicating in its home network.
Therefore, it would be desirable to take advantage of this standards-based technology with a dual-mode mobile phone even in the situation where the phone is communicating in its home network which uses a proprietary technology.